libbey



(No Model.) .I

H. W.LIBBEY.

WOOD SCREW. No. 422,307. Patented Feb. 25, I890.

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-- bility of splitting the material than screws 4e face with which the wood is in contact the NITED STATES FFICE.

P TENT WOU D SC REW.

SPECIFICATION forming art of letters Patent No. 422,307, dated February 25,1890. Application filed June 26, 1889. Serial No. 315,617. (No model.)

5 Massachusetts, have invented certain new and useful Improvements in Wood-Screws, of which the following, taken in connection with the accompanyingdrawings, is a specification, The object of my invention is to produce a wood-screw that can be inserted with less lianow in use; and the invention consists in making the thread slightly thicker and dividing its periphery by a V-shaped groove, so as to present two cutting-edges on each thread; and the invention further consists inmaking the head with a square hole, as hereinafter fully described, and pointed out in the claims. -Referring to the accompanying drawings,

Fig. 2 is' alongitudinal section through the center of the same. Fig.3 is a plan or top view of the head, showing the square hole and outthe 'nick. -.Eigs. 5 and 6' are respectively nick. .Fig. 4 is a similarview of a head with side view and view 0f the end of a screwdriver adapted "to-drive the screw-with a square hole and nick.

thread is slightly thicker-than the thread of an ordinary wood-screw, and its periphery is two cutting-edges b b, .or, as it were, a double same, 'whilea better hold is obtained, because as there is at least one-third more lateral sur- Figure 1 represents a side view of awoodscrew constructed according to my invention.

A-represents the head} B, the barrel or stem; 'O,-the thread, and D the point, The

screw is easier forced home and has better drawing and holding capacity.

In the head I form a square hole or recess (1, which may be in connection with the ordinary nick e, as shown in Fig. 3, or the head may be formed without the nick, as shown in Fig. 4. By means of this square hole or recess (1 the screw can be driven in or withdrawn from the wood by any square piece of metal being inserted in the same, and if the head is formed with a nick e, as in Fig. 3, a screwdriver F, with a square projection f on its lower end, maybe employed, and the square end fwill keep the screw-driver from slipping out of the nick and spoiling the edges thereof, as with screw-heads with only the ordinary nick; but if desired the ordinary nick alone may be employed.

\Vhat I claim as my invention is- Y 5 6 1. A wood-screw. the thread of which is divided by a V-shaped groove, so asto produce two cutting-edges on the thread, substantially as shown and described.

2. A wood-screw consisting-of the head. A stem B, and thread 0, said thread being d1- vided by a V-shaped groove a, and having two cutting edges b b, substantially as shown and described. I V

3. A-wood-screw with a flat-facedhead'having a square hole in its center, a stem under the head, and a double screw-thread formed by a V-shaped groove in the periphery of the to "this specification, in the presence'of two subscribing witnesses, on this 29th day off May, A. 11.1880,

. HOSEA LIBBEY. Witnesses:

A Cass. Sienna, 1 1EDWINPLANTA.' I

1 thread, substantially as shown and described.

In testimony whereof Ihave signed my namev 

